Damages of wind turbine blade trailing edge: Forms, location, and root causes

• 99 blades of 100 kW and 300 kW power wind turbines were inspected.
• Longitudinal cracks and transverse cracks were the obvious damages.
• Transverse cracks were classified into 5 sub-forms.
• Damage distribution gave an estimation of potential location on the blade.
• The possible root causes of trailing edge damage were discussed.

The geometrical form and the manufacturing technique make the trailing edge of the wind turbine blade more susceptible to damage. In this study the trailing edge in a number of 81 blades of 100 kW wind turbines and 18 blades of 300 kW wind turbines of working life ranging between 6.5 × 107 and 1.1 × 108 cycles were completely visually scanned. The different damages were classified and allocated in their exact position relative to the blade length. Cracks in different orientations with the blade length were the frequent types of damages which found on the trailing edge. First, longitudinal cracks (LCs) that found along the blade trailing edge from the blade root to the tip were in lengths that varied from a few centimeters up to around 1.35 m. Second, transverse cracks (TCs) were found in either simple TCs which growing on one shell at the trailing edge or round TCs which growing across the two shells. TCs lengths were ranging from 20 to 50 mm. Third, edge damages were detected in the form of edge cuts or crushing. The possible root causes of the different types of cracks have been discussed.